<!DOCTYPE html PUBLIC "-//W3C//DTD XHTML 1.0 Transitional//EN" "http://www.w3.org/TR/xhtml1/DTD/xhtml1-transitional.dtd">
<html xmlns="http://www.w3.org/1999/xhtml" xml:lang="en" lang="en">
<head><meta http-equiv="content-type" content="text/html; charset=UTF-8" />
<title>RandomUtil xref</title>
<link type="text/css" rel="stylesheet" href="../../../../stylesheet.css" />
</head>
<body>
<div id="overview"><a href="../../../../../../../../../feilong-core/target/site/apidocs/com/feilong/core/util/RandomUtil.html">View Javadoc</a></div><pre>
<a class="jxr_linenumber" name="L1" href="#L1">1</a>   <em class="jxr_comment">/*</em>
<a class="jxr_linenumber" name="L2" href="#L2">2</a>   <em class="jxr_comment"> * Copyright (C) 2008 feilong</em>
<a class="jxr_linenumber" name="L3" href="#L3">3</a>   <em class="jxr_comment"> *</em>
<a class="jxr_linenumber" name="L4" href="#L4">4</a>   <em class="jxr_comment"> * Licensed under the Apache License, Version 2.0 (the "License");</em>
<a class="jxr_linenumber" name="L5" href="#L5">5</a>   <em class="jxr_comment"> * you may not use this file except in compliance with the License.</em>
<a class="jxr_linenumber" name="L6" href="#L6">6</a>   <em class="jxr_comment"> * You may obtain a copy of the License at</em>
<a class="jxr_linenumber" name="L7" href="#L7">7</a>   <em class="jxr_comment"> *</em>
<a class="jxr_linenumber" name="L8" href="#L8">8</a>   <em class="jxr_comment"> *         <a href="http://www.apache.org/licenses/LICENSE-2." target="alexandria_uri">http://www.apache.org/licenses/LICENSE-2.</a>0</em>
<a class="jxr_linenumber" name="L9" href="#L9">9</a>   <em class="jxr_comment"> *</em>
<a class="jxr_linenumber" name="L10" href="#L10">10</a>  <em class="jxr_comment"> * Unless required by applicable law or agreed to in writing, software</em>
<a class="jxr_linenumber" name="L11" href="#L11">11</a>  <em class="jxr_comment"> * distributed under the License is distributed on an "AS IS" BASIS,</em>
<a class="jxr_linenumber" name="L12" href="#L12">12</a>  <em class="jxr_comment"> * WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.</em>
<a class="jxr_linenumber" name="L13" href="#L13">13</a>  <em class="jxr_comment"> * See the License for the specific language governing permissions and</em>
<a class="jxr_linenumber" name="L14" href="#L14">14</a>  <em class="jxr_comment"> * limitations under the License.</em>
<a class="jxr_linenumber" name="L15" href="#L15">15</a>  <em class="jxr_comment"> */</em>
<a class="jxr_linenumber" name="L16" href="#L16">16</a>  <strong class="jxr_keyword">package</strong> com.feilong.core.util;
<a class="jxr_linenumber" name="L17" href="#L17">17</a>  
<a class="jxr_linenumber" name="L18" href="#L18">18</a>  <strong class="jxr_keyword">import</strong> java.util.Random;
<a class="jxr_linenumber" name="L19" href="#L19">19</a>  
<a class="jxr_linenumber" name="L20" href="#L20">20</a>  <strong class="jxr_keyword">import</strong> org.apache.commons.lang3.RandomStringUtils;
<a class="jxr_linenumber" name="L21" href="#L21">21</a>  <strong class="jxr_keyword">import</strong> org.apache.commons.lang3.Validate;
<a class="jxr_linenumber" name="L22" href="#L22">22</a>  
<a class="jxr_linenumber" name="L23" href="#L23">23</a>  <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="L24" href="#L24">24</a>  <em class="jxr_javadoccomment"> * 随机数工具类.</em>
<a class="jxr_linenumber" name="L25" href="#L25">25</a>  <em class="jxr_javadoccomment"> * </em>
<a class="jxr_linenumber" name="L26" href="#L26">26</a>  <em class="jxr_javadoccomment"> * &lt;ul&gt;</em>
<a class="jxr_linenumber" name="L27" href="#L27">27</a>  <em class="jxr_javadoccomment"> * &lt;li&gt;{@link java.lang.Math#random()}底层也是调用的 new Random(),值＝Random nextDouble()&lt;/li&gt;</em>
<a class="jxr_linenumber" name="L28" href="#L28">28</a>  <em class="jxr_javadoccomment"> * &lt;li&gt;把 {@link java.util.Random}对象作为一个全局实例(static)来使用.Java中 {@link java.util.Random} 是线程安全的(内部进行了加锁处理);&lt;/li&gt;</em>
<a class="jxr_linenumber" name="L29" href="#L29">29</a>  <em class="jxr_javadoccomment"> * &lt;li&gt;伪随机数&lt;/li&gt;</em>
<a class="jxr_linenumber" name="L30" href="#L30">30</a>  <em class="jxr_javadoccomment"> * &lt;li&gt;生成随机数的算法有很多种,最简单也是最常用的就是 "线性同余法":第n+1个数=(第n个数*29+37) % 1000,其中%是"求余数"运算符.&lt;/li&gt;</em>
<a class="jxr_linenumber" name="L31" href="#L31">31</a>  <em class="jxr_javadoccomment"> * &lt;/ul&gt;</em>
<a class="jxr_linenumber" name="L32" href="#L32">32</a>  <em class="jxr_javadoccomment"> *</em>
<a class="jxr_linenumber" name="L33" href="#L33">33</a>  <em class="jxr_javadoccomment"> * @author &lt;a href="<a href="http://feitianbenyue.iteye.com/" target="alexandria_uri">http://feitianbenyue.iteye.com/</a>"&gt;feilong&lt;/a&gt;</em>
<a class="jxr_linenumber" name="L34" href="#L34">34</a>  <em class="jxr_javadoccomment"> * @see java.lang.Math#random()</em>
<a class="jxr_linenumber" name="L35" href="#L35">35</a>  <em class="jxr_javadoccomment"> * @see org.apache.commons.lang3.RandomUtils</em>
<a class="jxr_linenumber" name="L36" href="#L36">36</a>  <em class="jxr_javadoccomment"> * @see org.apache.commons.lang3.RandomStringUtils</em>
<a class="jxr_linenumber" name="L37" href="#L37">37</a>  <em class="jxr_javadoccomment"> * @since 1.0.0</em>
<a class="jxr_linenumber" name="L38" href="#L38">38</a>  <em class="jxr_javadoccomment"> */</em>
<a class="jxr_linenumber" name="L39" href="#L39">39</a>  <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">final</strong> <strong class="jxr_keyword">class</strong> <a href="../../../../com/feilong/core/util/RandomUtil.html">RandomUtil</a>{
<a class="jxr_linenumber" name="L40" href="#L40">40</a>  
<a class="jxr_linenumber" name="L41" href="#L41">41</a>      <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="L42" href="#L42">42</a>  <em class="jxr_javadoccomment">     * Random object used by random method.</em>
<a class="jxr_linenumber" name="L43" href="#L43">43</a>  <em class="jxr_javadoccomment">     * </em>
<a class="jxr_linenumber" name="L44" href="#L44">44</a>  <em class="jxr_javadoccomment">     * &lt;p&gt;</em>
<a class="jxr_linenumber" name="L45" href="#L45">45</a>  <em class="jxr_javadoccomment">     * 为了确保同一毫秒不能返回相同的值,不同声明在方法里面.&lt;br&gt;</em>
<a class="jxr_linenumber" name="L46" href="#L46">46</a>  <em class="jxr_javadoccomment">     * 把Random对象作为一个全局实例(static)来使用. Java中Random是线程安全的(内部进行了加锁处理);</em>
<a class="jxr_linenumber" name="L47" href="#L47">47</a>  <em class="jxr_javadoccomment">     * &lt;/p&gt;</em>
<a class="jxr_linenumber" name="L48" href="#L48">48</a>  <em class="jxr_javadoccomment">     * </em>
<a class="jxr_linenumber" name="L49" href="#L49">49</a>  <em class="jxr_javadoccomment">     * @see org.apache.commons.lang3.RandomUtils</em>
<a class="jxr_linenumber" name="L50" href="#L50">50</a>  <em class="jxr_javadoccomment">     * @since 1.0.7</em>
<a class="jxr_linenumber" name="L51" href="#L51">51</a>  <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="L52" href="#L52">52</a>      <strong class="jxr_keyword">private</strong> <strong class="jxr_keyword">static</strong> <strong class="jxr_keyword">final</strong> Random JVM_RANDOM = <strong class="jxr_keyword">new</strong> Random();
<a class="jxr_linenumber" name="L53" href="#L53">53</a>  
<a class="jxr_linenumber" name="L54" href="#L54">54</a>      <em class="jxr_javadoccomment">/** Don't let anyone instantiate this class. */</em>
<a class="jxr_linenumber" name="L55" href="#L55">55</a>      <strong class="jxr_keyword">private</strong> <a href="../../../../com/feilong/core/util/RandomUtil.html">RandomUtil</a>(){
<a class="jxr_linenumber" name="L56" href="#L56">56</a>          <em class="jxr_comment">//AssertionError不是必须的. 但它可以避免不小心在类的内部调用构造器. 保证该类在任何情况下都不会被实例化.</em>
<a class="jxr_linenumber" name="L57" href="#L57">57</a>          <em class="jxr_comment">//see 《Effective Java》 2nd</em>
<a class="jxr_linenumber" name="L58" href="#L58">58</a>          <strong class="jxr_keyword">throw</strong> <strong class="jxr_keyword">new</strong> AssertionError(<span class="jxr_string">"No "</span> + getClass().getName() + <span class="jxr_string">" instances for you!"</span>);
<a class="jxr_linenumber" name="L59" href="#L59">59</a>      }
<a class="jxr_linenumber" name="L60" href="#L60">60</a>  
<a class="jxr_linenumber" name="L61" href="#L61">61</a>      <em class="jxr_comment">// ********************************************************************</em>
<a class="jxr_linenumber" name="L62" href="#L62">62</a>  
<a class="jxr_linenumber" name="L63" href="#L63">63</a>      <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="L64" href="#L64">64</a>  <em class="jxr_javadoccomment">     * 生成一个指定长度&lt;code&gt;length&lt;/code&gt;的 &lt;b&gt;随机正整数&lt;/b&gt;.</em>
<a class="jxr_linenumber" name="L65" href="#L65">65</a>  <em class="jxr_javadoccomment">     * </em>
<a class="jxr_linenumber" name="L66" href="#L66">66</a>  <em class="jxr_javadoccomment">     * &lt;h3&gt;示例:&lt;/h3&gt;</em>
<a class="jxr_linenumber" name="L67" href="#L67">67</a>  <em class="jxr_javadoccomment">     * &lt;blockquote&gt;</em>
<a class="jxr_linenumber" name="L68" href="#L68">68</a>  <em class="jxr_javadoccomment">     * </em>
<a class="jxr_linenumber" name="L69" href="#L69">69</a>  <em class="jxr_javadoccomment">     * &lt;pre class="code"&gt;</em>
<a class="jxr_linenumber" name="L70" href="#L70">70</a>  <em class="jxr_javadoccomment">     * RandomUtil.createRandomWithLength(2)</em>
<a class="jxr_linenumber" name="L71" href="#L71">71</a>  <em class="jxr_javadoccomment">     * 生成的结果是可能是 89</em>
<a class="jxr_linenumber" name="L72" href="#L72">72</a>  <em class="jxr_javadoccomment">     * &lt;/pre&gt;</em>
<a class="jxr_linenumber" name="L73" href="#L73">73</a>  <em class="jxr_javadoccomment">     * </em>
<a class="jxr_linenumber" name="L74" href="#L74">74</a>  <em class="jxr_javadoccomment">     * &lt;/blockquote&gt;</em>
<a class="jxr_linenumber" name="L75" href="#L75">75</a>  <em class="jxr_javadoccomment">     *</em>
<a class="jxr_linenumber" name="L76" href="#L76">76</a>  <em class="jxr_javadoccomment">     * @param length</em>
<a class="jxr_linenumber" name="L77" href="#L77">77</a>  <em class="jxr_javadoccomment">     *            设定所取出随机数的长度.</em>
<a class="jxr_linenumber" name="L78" href="#L78">78</a>  <em class="jxr_javadoccomment">     * @return 如果 &lt;code&gt;length&lt;/code&gt; {@code &lt;=0} ,抛出 {@link IllegalArgumentException}</em>
<a class="jxr_linenumber" name="L79" href="#L79">79</a>  <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="L80" href="#L80">80</a>      <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">static</strong> <strong class="jxr_keyword">long</strong> createRandomWithLength(<strong class="jxr_keyword">int</strong> length){
<a class="jxr_linenumber" name="L81" href="#L81">81</a>          Validate.isTrue(length &gt; 0, <span class="jxr_string">"input param [length] must &gt;0,but is [%s]"</span>, length);
<a class="jxr_linenumber" name="L82" href="#L82">82</a>          <strong class="jxr_keyword">long</strong> num = 1;
<a class="jxr_linenumber" name="L83" href="#L83">83</a>          <strong class="jxr_keyword">for</strong> (<strong class="jxr_keyword">int</strong> i = 0; i &lt; length; ++i){
<a class="jxr_linenumber" name="L84" href="#L84">84</a>              num = num * 10;
<a class="jxr_linenumber" name="L85" href="#L85">85</a>          }
<a class="jxr_linenumber" name="L86" href="#L86">86</a>  
<a class="jxr_linenumber" name="L87" href="#L87">87</a>          <em class="jxr_comment">// 该值大于等于 0.0 且小于 1.0 正号的 double 值</em>
<a class="jxr_linenumber" name="L88" href="#L88">88</a>          <strong class="jxr_keyword">double</strong> random = JVM_RANDOM.nextDouble();
<a class="jxr_linenumber" name="L89" href="#L89">89</a>          random = random &lt; 0.1 ? random + 0.1 : random;<em class="jxr_comment">// 可能出现 0.09346924349151808</em>
<a class="jxr_linenumber" name="L90" href="#L90">90</a>          <strong class="jxr_keyword">return</strong> (<strong class="jxr_keyword">long</strong>) (random * num);
<a class="jxr_linenumber" name="L91" href="#L91">91</a>      }
<a class="jxr_linenumber" name="L92" href="#L92">92</a>  
<a class="jxr_linenumber" name="L93" href="#L93">93</a>      <em class="jxr_comment">// ******************************createRandomFromString**********************************</em>
<a class="jxr_linenumber" name="L94" href="#L94">94</a>      <em class="jxr_javadoccomment">/**</em>
<a class="jxr_linenumber" name="L95" href="#L95">95</a>  <em class="jxr_javadoccomment">     * 随机抽取字符串&lt;code&gt;char&lt;/code&gt;,拼接成指定长度&lt;code&gt;length&lt;/code&gt;的字符串.</em>
<a class="jxr_linenumber" name="L96" href="#L96">96</a>  <em class="jxr_javadoccomment">     * </em>
<a class="jxr_linenumber" name="L97" href="#L97">97</a>  <em class="jxr_javadoccomment">     * &lt;h3&gt;说明:&lt;/h3&gt;</em>
<a class="jxr_linenumber" name="L98" href="#L98">98</a>  <em class="jxr_javadoccomment">     * &lt;blockquote&gt;</em>
<a class="jxr_linenumber" name="L99" href="#L99">99</a>  <em class="jxr_javadoccomment">     * &lt;ol&gt;</em>
<a class="jxr_linenumber" name="L100" href="#L100">100</a> <em class="jxr_javadoccomment">     * &lt;li&gt;常用于生成验证码&lt;/li&gt;</em>
<a class="jxr_linenumber" name="L101" href="#L101">101</a> <em class="jxr_javadoccomment">     * &lt;/ol&gt;</em>
<a class="jxr_linenumber" name="L102" href="#L102">102</a> <em class="jxr_javadoccomment">     * &lt;/blockquote&gt;</em>
<a class="jxr_linenumber" name="L103" href="#L103">103</a> <em class="jxr_javadoccomment">     * </em>
<a class="jxr_linenumber" name="L104" href="#L104">104</a> <em class="jxr_javadoccomment">     * &lt;h3&gt;示例:&lt;/h3&gt;</em>
<a class="jxr_linenumber" name="L105" href="#L105">105</a> <em class="jxr_javadoccomment">     * &lt;blockquote&gt;</em>
<a class="jxr_linenumber" name="L106" href="#L106">106</a> <em class="jxr_javadoccomment">     * </em>
<a class="jxr_linenumber" name="L107" href="#L107">107</a> <em class="jxr_javadoccomment">     * &lt;pre class="code"&gt;</em>
<a class="jxr_linenumber" name="L108" href="#L108">108</a> <em class="jxr_javadoccomment">     * RandomUtil.createRandomFromString({@link com.feilong.core.Alphabet#DECIMAL_AND_LETTERS Alphabet.DECIMAL_AND_LETTERS}, 5)</em>
<a class="jxr_linenumber" name="L109" href="#L109">109</a> <em class="jxr_javadoccomment">     * </em>
<a class="jxr_linenumber" name="L110" href="#L110">110</a> <em class="jxr_javadoccomment">     * 从 {@link com.feilong.core.Alphabet#DECIMAL_AND_LETTERS  Alphabet.DECIMAL_AND_LETTERS} 随机抽取字符,组成长度是5的字符串</em>
<a class="jxr_linenumber" name="L111" href="#L111">111</a> <em class="jxr_javadoccomment">     * 生成的结果是可能是IFSMB</em>
<a class="jxr_linenumber" name="L112" href="#L112">112</a> <em class="jxr_javadoccomment">     * &lt;/pre&gt;</em>
<a class="jxr_linenumber" name="L113" href="#L113">113</a> <em class="jxr_javadoccomment">     * </em>
<a class="jxr_linenumber" name="L114" href="#L114">114</a> <em class="jxr_javadoccomment">     * &lt;/blockquote&gt;</em>
<a class="jxr_linenumber" name="L115" href="#L115">115</a> <em class="jxr_javadoccomment">     * </em>
<a class="jxr_linenumber" name="L116" href="#L116">116</a> <em class="jxr_javadoccomment">     * @param str</em>
<a class="jxr_linenumber" name="L117" href="#L117">117</a> <em class="jxr_javadoccomment">     *            被抽取的字符串,比如{@link com.feilong.core.Alphabet#DECIMAL_AND_LETTERS}</em>
<a class="jxr_linenumber" name="L118" href="#L118">118</a> <em class="jxr_javadoccomment">     * @param length</em>
<a class="jxr_linenumber" name="L119" href="#L119">119</a> <em class="jxr_javadoccomment">     *            指定字符串长度,比如 5</em>
<a class="jxr_linenumber" name="L120" href="#L120">120</a> <em class="jxr_javadoccomment">     * @return 如果 &lt;code&gt;str&lt;/code&gt; 是null,抛出 {@link NullPointerException}&lt;br&gt;</em>
<a class="jxr_linenumber" name="L121" href="#L121">121</a> <em class="jxr_javadoccomment">     *         如果 &lt;code&gt;str&lt;/code&gt; 是blank,抛出 {@link IllegalArgumentException}&lt;br&gt;</em>
<a class="jxr_linenumber" name="L122" href="#L122">122</a> <em class="jxr_javadoccomment">     *         如果 &lt;code&gt;length&lt;/code&gt; {@code &lt;=0}, 抛出 {@link IllegalArgumentException}</em>
<a class="jxr_linenumber" name="L123" href="#L123">123</a> <em class="jxr_javadoccomment">     * </em>
<a class="jxr_linenumber" name="L124" href="#L124">124</a> <em class="jxr_javadoccomment">     * @see org.apache.commons.lang3.RandomStringUtils#random(int, String)</em>
<a class="jxr_linenumber" name="L125" href="#L125">125</a> <em class="jxr_javadoccomment">     */</em>
<a class="jxr_linenumber" name="L126" href="#L126">126</a>     <strong class="jxr_keyword">public</strong> <strong class="jxr_keyword">static</strong> String createRandomFromString(String str,<strong class="jxr_keyword">int</strong> length){
<a class="jxr_linenumber" name="L127" href="#L127">127</a>         Validate.notBlank(str, <span class="jxr_string">"str can't be null/empty!"</span>);
<a class="jxr_linenumber" name="L128" href="#L128">128</a>         Validate.isTrue(length &gt; 0, <span class="jxr_string">"input param [length] must &gt;0,but is [%s]"</span>, length);
<a class="jxr_linenumber" name="L129" href="#L129">129</a>         <strong class="jxr_keyword">return</strong> RandomStringUtils.random(length, str);
<a class="jxr_linenumber" name="L130" href="#L130">130</a>     }
<a class="jxr_linenumber" name="L131" href="#L131">131</a> 
<a class="jxr_linenumber" name="L132" href="#L132">132</a> }
</pre>
<hr/>
<div id="footer">Copyright &#169; 2008&#x2013;2017 <a href="http://venusdrogon.github.io/feilong-platform/">feiLong</a>. All rights reserved.</div>
</body>
</html>
